Hybrid drive system comprising a hydrodynamic clutch particularly for motor vehicles

ABSTRACT

A drive system for a motor vehicle is provided. The drive system has a drive assembly, at least one power transmission unit that is coupled with the drive assembly and an electrical machine coupled at least indirectly with the drive assembly. The power transmission unit has at least one starting element with a hydrodynamic clutch and a bridging clutch. A rotor or armature of the electrical machine is arranged coaxially to the hydrodynamic clutch and can be coupled with it in a torsionally rigid manner.

The invention concerns a drive system, particularly for motor vehicles,specifically with the features taken from the preamble of claim 1.

Drive systems, particularly mechanical drive systems with an integratedelectrical machine functioning as a starter generator, are known in aplurality of designs. Reference is made by way of example to acompilation of Dr.-Eng. Wolfgang Reick, LuK & Co, Bühl,“Startergenerator im Antriebsstrang” [Starter Generators in the DriveTrain”], published at http://www.luk.de/Bibliothek/Vortraege.html. Astarter generator of this kind is understood here to refer to anelectrical machine, the rotor of which is mounted directly on thecrankshaft or else is arranged parallel to the latter and which can workboth as a generator and as a motor. The electrical machine is employedfor starting the internal combustion engine and, further, as a generatorfor energy recuperation from the drive system. In particular, therecuperation of energy in, for example, the coasting or deceleratingmode is gaining ever increasing importance owing to the constantincrease in the number of electrically driven components. In order toprovide these functions, a certain dimensioning of the electricalmachine is necessary and thus the system cannot be offered at anespecially favorable price; therefore, additional functions are beingincreasingly assigned to this unit. Such additional functions are:start/stop function for soft start, direct start, impulse start,booster, energy recuperation in coasting, active synchronization, anddamping. The electrical machine can be disposed here coaxially oreccentrically for the coupling between the internal combustion engineand the drive train, usually a transmission. Depending on thearrangement, the electrical machine is arranged through one or twoclutches so that it can be disengaged from the drive train. A design ofa starter generator for automatic transmissions with converter may befound on page 53 of the above article. In it, the starter generator isadjoined to the hydrodynamic speed/torque converter. In the structuralspace designed for the current lockup clutch, only one further secondclutch is integrated, which can disengage the motor from the pump case.The first clutch serves here to make a connection between the crankshaftand the rotor and the second clutch represents the usual lockup clutch.If the first clutch is opened, the internal combustion engine can bestopped and the electrical machine will continue to operate.Accordingly, this allows all states that are possible with a two-clutchsolution to be provided, that is, particularly the function as a boosterand as a starter and the recuperation of energy. An important drawbackof the use of a converter in the automatic transmission consists of thefact that, also particularly at low temperatures, in spite of thepossibility of the direct start or of an impulse start via theelectrical machine, the power transmission via the hydrodynamicconverter is thereby very unsatisfactory, especially in low gear. Theadvantages that ensue through the use of the starter generator are inturn eliminated by the poor cold start behavior in this state, which,particularly for use in automatic transmissions or automated shifttransmissions, can be problematic at corresponding latitudes with attimes very low temperatures. Further, the complete unit consisting ofelectrical machine and starting component has a very wide constructionin the axial and radial directions. The necessary structural space isdefined here essentially by the structural space required for installingthe hydrodynamic speed/torque converter and thus the still remainingpossibilities available for integration of the electrical machine. Afurther important drawback consists in the nonexistence of a possibilityfor adjusting the power input and for control of the power input of thehydrodynamic speed/torque converter. Accordingly, in all operatingstates, the maximum power possible is immediately taken up by the latterand this can lead, under certain circumstances, to an undesired drivingresponse during starting operation and possibly also to a suddenstalling of the driving engine.

The invention is therefore based on the object of further developing adrive system of the type mentioned in the beginning in such a way thatthe drawbacks cited are avoided. Specifically, a solution with improvedcold start behavior is to be proposed. The solution should further besuitable for any kind of transmission, particularly automated shifttransmissions, shift transmissions, and CVTs and it should becharacterized by a reduced structural space in the axial direction andalso in the radial direction compared to designs of the prior art.

The solution of the invention is characterized by the features of claim1. Advantageous embodiments are presented in the subclaims.

A drive system, particularly for motor vehicles, with a drive assemblyand at least one power transmission unit that is coupled with the driveassembly and one electrical machine that is coupled at least indirectlywith the drive assembly is designed in accordance with the invention insuch a way that the power transmission unit is free of a hydrodynamicspeed/torque converter and instead comprises a hydrodynamic clutch,which is adjoined to the electrical machine. The electrical machine isarranged here coaxially to the hydrodynamic clutch and can be connectedto it in a torsionally rigid manner. This means that the rotor isconnected in a torsionally rigid manner to the hydrodynamic clutcheither constantly or else it is only at times connected to it. Involvedin the case of the hydrodynamic clutch is a hydrodynamic component thatis characterized by the presence of two blade wheels, a primary bladewheel and a secondary blade wheel, which, as a rule, form with eachother a torus-shaped operating chamber. Here, the hydrodynamic clutch isfree of further blade wheels, such as, for example a guide wheel. Thefunction of the hydrodynamic clutch consists in power transmissionbetween the primary blade wheel and the secondary blade wheel when theirmoments of inertia are identical, it being possible with this component,in contrast to the hydrodynamic speed/torque converter, to make only onespeed conversion.

The inventors have recognized that, in order to eliminate the problemsof a design in accordance with the prior art, the hydrodynamic componentin the form of the hydrodynamic speed/torque converter can be replacedby a hydrodynamic clutch, because the latter, especially at lowtemperatures, that is, in the cold state, is characterized by anappreciably lower power input than the hydrodynamic converter. Further,the use of a hydrodynamic clutch offers the advantage that the requireddesign length in the axial direction as well as in the radial directioncan be minimized, it being possible to enhance this effect still furtherby the construction of diagonal blading. The lower power input onstarting with a cold operating medium is made possible by the creationof a free flow toward the converter with forced flow in the torus-shapedoperating chamber.

A further important advantage of the system of a combination consistingof a hydrodynamic starting element in the form of a hydrodynamic clutch,which is coupled with an electrical machine functioning as a startergenerator, the rotor or armature of this electrical machine beingarranged coaxially to the hydrodynamic clutch, consists in additionallyacquired structural space both in the radial and in the axialdirections, which can be used for other components. This results inabsolutely efficient integration advantages compared to a solution witha hydrodynamic speed/torque converter, by means of which, in particular,the increased demands on the increasingly reduced structural spaceavailable for the use of drive systems for vehicles can be met.

According to an advantageous embodiment, the hydrodynamic clutch can beoperated at least with partial filling. This means that, for fulloperating capability, there does not have to be a complete filling and,further, with the hydrodynamic clutch, it is possible to activelycontrol or to regulate the speed on the driving side, that is, of thepart coupled with the secondary blade wheel, and/or the speed of theparts of the drive train coupled with the primary blade wheel. Thisoffers the advantage that it is possible to respond here to differentpower demands. For this purpose, the hydrodynamic clutch is preferablycontrollable, the control occurring through the change in the fillingratio. In accordance therewith, a device for influencing the fillingratio of the hydrodynamic clutch is provided. This can be designed in avariety of ways. Here, only a design of a hydrodynamic clutch with aclosed circuit, corresponding to the flow circuit adjusted in thetorus-shaped operating chamber, which is conveyed outside of thetorus-shaped operating chamber and is constructed in a pressure-tightmanner, is mentioned as a representative example. The closed circuit iscoupled here with a supply source of operating medium, this couplingalso being made in a pressure-tight manner. Preferably, the operatingmedium source is designed in the form of an operating medium pan, thechange in the filling ratio being undertaken through the influence ofapplied pressure on the operating medium level. As an operating mediumpan, it is possible to use here a separate supply system of operatingmedium, such as, for example, an oil pan, when the hydrodynamic clutchas a starting component is integrated in a transmission modular unit,the operating medium pan of the transmission modular unit, or anoperating medium pan separately assigned to the starting component ofthe hydrodynamic clutch. Besides the controllability of the hydrodynamicclutch, it can also be integrated into regulating operations; forexample, a regulation of the filling ratio and thus of the power inputcan occur.

The hydrodynamic clutch functions as a starting component and iscoupled, either directly or, for example, through the intermediateconnection of a flywheel, with the drive assembly, which, as a rule, isdesigned in the form of an internal combustion engine. The couplingoccurs here via the primary blade wheel. In a plurality of designs, thelatter is connected in a torsionally rigid manner with a so-calledprimary wheel shell, which surrounds the secondary blade wheel at leastin part in the axial direction and in the circumferential direction. Thestarting element forms a starting unit with the bridging clutch. Interms of its arrangement in space, this starting unit is, as a rule,placed after a transmission. Both of these—the starting unit and thetransmission—then form a complete modular unit. Here, for solutions as aseparate prefabricated module, the starting unit can be constructed withits own casing, which is flange-mounted on the transmission housing inorder to form a complete modular unit consisting of starting unit andtransmission. This solution is chosen, above all, for starting elementsin the form of hydrodynamic clutches with additional functions and withadditional elements allocated to it. In this case, the starting unit, asa module, can be inspected independently. For the design of the startingunit as an independent module, the electrical machine is integrated intoit as well. Another possibility consists in also integrating thecombination consisting of starting unit and electrical machine into thehousing of the transmission, the transmission housing being constructedin this case with a compartment into which the prefabricated module—inthis case, as a rule, without its own casing—can be inserted and withwhich the speed/torque converter units of the transmission can becoupled. The term transmission is to be understood very generally andincludes any kind of speed/torque converter units which are connecteddownstream to a starting unit and can be coupled to it. For use in motorvehicle construction, the speed/torque converter units of thetransmission are formed, as a rule, from mechanical speed/torqueconverter units. As a rule, these involve output stages, which, forexample, can be formed from planetary gearsets or spur wheel gearsets.Also conceivable are constructions of the transmission as an infinitelyvariable transmission, in which, here, as a rule, chain and belttransmissions are put to use. In this way, it is also possible tocombine the possibilities of infinitely variable power transmission withthose of a fixed transmission ratio. The concrete design of thetransmission as well as of the combination and constructionalamalgamation of starting unit with integrated starter generator andtransmission lies here in the judgement of the person skilled in the artand depends on the concrete case of application and the constraintsensuing therefrom.

As a rule, an engaging and disengaging clutch is arranged parallel tothe hydrodynamic clutch as a starting element and serves for bridging.This bridging is realized here through the torsionally coupling betweenthe primary blade wheel and the secondary blade wheel. This couplinginvolves, as a rule, a friction clutch, preferably a disk clutch.

For the design of the torsionally rigid coupling between the rotor orarmature of the electrical machine and the hydrodynamic clutch, thereare a multitude of possibilities. According to a first design, the rotoror armature of the electrical machine is coupled in a torsionally rigidmanner with the primary blade wheel, preferably with the primary bladewheel shell. The rotor or armature of the electrical machine can therebyform a constructional unit with the primary blade wheel shell, theprimary blade wheel shell and the armature being designed either asintegral modular units or else being coupled to each other via means fortorsionally rigid connection. In both cases, the connection between thearmature or rotor of the electrical machine and the primary blade wheelof the hydrodynamic clutch is free of means for alternative coupling ordecoupling from each other in the form of, for example, engaging anddisengaging clutches. This means that there is always a torsionallyrigid connection between the armature or rotor of the electrical machineand the primary blade wheel of the hydrodynamic clutch. The connectionbetween the connection of the rotor of the electrical machine with theprimary blade wheel of the hydrodynamic clutch and the drive assemblycan

-   -   a) be free of means for alternative coupling or decoupling of        the drive assembly from the connection between the electrical        machine and the primary blade wheel or else    -   b) provide for means for the alternative coupling or decoupling        of the connection between the electrical machine and primary        blade wheel and the drive assembly.

In the former case, the rotor of the electrical machine is always indriving connection with the drive assembly, particularly with thecrankshaft in the case of construction as an internal combustion engine.This means that, in this state, a starting of the internal combustionengine is possible. Further, the electrical machine can also assist fora short time the internal combustion engine and thus act as a booster.The hydrodynamic clutch is preferably emptied during the startingoperation. In the booster function mode, it is filled. In analogy, thebridging clutch is preferably opened during the starting operation.

In coasting operation, power transmission occurs from the output drive,that is, as a rule, via the transmission to the internal combustionengine, and a portion of the power can also be converted via theelectrical machine, which, in this case, is operated as a generator,into electrical power and made available to the on-board electricalsystem. Furthermore, in normal operation, that is, for powertransmission from the internal combustion engine to the output drive,corresponding to the driving of the electrical machine when the rotor iscoupled, the electrical machine takes up power and, in this case, isoperated as a generator and makes available the converted electricalpower to the on-board electrical system or to an energy storage device.In coasting operation, in order to use completely the power introducedvia the drive system for conversion into electrical power, thedeceleration losses by the internal combustion engine can be minimizedthrough the solution described under b) by interrupting the connectionbetween the electrical machine and the driving engine. The powerfraction that otherwise is used up through the internal friction of theinternal combustion engine, when there is a constant connection of therotor of the electrical machine with the internal combustion engine incoasting operation, can, in this case, then also be used additionallyfor conversion into electrical power.

For solutions with constant torsionally rigid connection between theprimary blade wheel of the hydrodynamic clutch and the rotor of theelectrical machine, there results, for the electrical machine in thecase of power transmission between the internal combustion engine andthe resulting mechanical power branch when the hydrodynamic clutch isbridged, the same functional possibilities, namely, assisting theinternal combustion engine and, further, in coasting operation, the useof the energy introduced via the output drive into the drive train forconversion into electrical power. In this case, the hydrodynamic clutchcan remain filled or else be emptied, the first possibility beingemployed preferably, because, here, it is possible to dispense withprolonged filling times.

According to a further development, means for alternative coupling anddecoupling, preferably in the form of a an engaging and disengagingclutch, are provided between the rotor of the electrical machine and theprimary blade wheel of the hydrodynamic clutch. This possibility offersthe advantage that, here, no complete separation of the drive train fromthe internal combustion engine is necessary for breaking the connectionbetween the rotor of the electrical machine and the drive assembly, butrather the coupling between the drive assembly and the hydrodynamicclutch or bridging clutch can remain in existence. However, here, too,for energy recuperation in coasting operation, the power fraction due tothe internal combustion engine is to be registered as lost power.

Further, for decoupling of the drive assembly between the drive assemblyand the hydrodynamic clutch, there exists the possibility of providing adevice for alternative interruption or realization of the power flowbetween the drive assembly and the hydrodynamic clutch as well as theelectrical machine.

All devices for coupling and decoupling are preferably designed in theform of engaging and disengaging clutches, particularly in the form ofdisk clutches.

According to a second solution approach, the electrical machine can beconnected in a torsionally rigid manner with the secondary blade wheel.This possibility of torsionally rigid connection can be afforded inaddition to the possible torsionally rigid coupling with the primaryblade wheel or else it can be provided as a second separate possiblesolution. In the first-mentioned case, the rotor of the electricalmachine is coupled in a torsionally rigid manner with the input of thebridging clutch and the primary blade wheel. For coupling with the inputof the bridging clutch, there exists nonetheless a torsionally rigidconnection between the rotor of the electrical machine and the primaryblade wheel, whereas the rotor is mechanically decoupled from thesecondary blade wheel by the bridging clutch. Only when the bridgingclutch is engaged is the rotor of the electrical machine connected in atorsionally rigid manner both with the primary blade wheel and with thesecondary blade wheel. For separation of the rotor from the drivingengine, either

-   -   a) a device for alternative coupling or decoupling of the rotor        from the primary blade wheel in the connection between the        primary blade wheel and the rotor and/or    -   b) a device for alternative coupling or decoupling of the        torsionally rigid connection of rotor and primary blade wheel        from the driving engine        is provided. Here, the variant b) can also be combined with a).        The function of the bridging clutch is then assumed in the case        mentioned under a) by both clutches, the one situated in front        of the rotor and the one situated in back of the rotor.

According to the second solution approach, the rotor is connected in atorsionally rigid manner only with the secondary blade wheel, it beingpossible for this connection to be characterized by a direct,torsionally rigid coupling or else by the provision of means for thealternative coupling and decoupling of the rotor from the secondaryblade wheel. In both cases, it is possible here, too, for the electricalmachine to assume the function of the starter for the drive assemblyand, in addition, as a booster, to assist at times the driving engine.For optimal energy recuperation, the drive assembly can be decoupledfrom the electrical machine, for example, by means of emptying thehydrodynamic clutch and simultaneous opening of the bridging clutch orelse through the provision of a further clutch between the starting unitand the drive assembly.

Under a further aspect of the invention, means for vibrational dampingare assigned to the starting unit. These can be arranged here at anysite in the drive system between the drive assembly and the transmissionor they can be arranged after the secondary blade wheel.

In regard to the electrical machines used, there exist no restrictionsfor the combination of the starting unit with the function of a startergenerator. Conceivable are all conventionally known electrical machines,synchronous machines and asynchronous machines, as well as synchronousmachines with transverse flow guide.

The solution of the invention is suitable for use in drive systems withshift transmissions, particularly in automatic transmissions orautomated shift transmissions.

The solution of the invention is explained below on the basis offigures. Shown therein in detail is the following:

FIG. 1 illustrates in a schematically greatly simplified depiction afirst embodiment of a starting unit of the invention in a drive system,on the basis of an excerpt from this, with torsionally rigid connectionbetween the rotor of the electrical machine and the primary blade wheel;

FIG. 2 illustrates a further development of an embodiment according toFIG. 1 with the additional possibility for the decoupling of the driveassembly from the torsionally rigid connection between the rotor and theprimary blade wheel;

FIG. 3 illustrates a further development of an embodiment according toFIG. 1 with additional possibility for the decoupling of the rotor fromthe primary blade wheel;

FIG. 4 illustrates in a schematically greatly simplified depiction asecond embodiment of a starting unit of the invention in a drive system,on the basis of an excerpt from it, with torsionally rigid connectionbetween the rotor of the electrical machine and the secondary bladewheel;

FIG. 5 illustrates a further development of an embodiment according toFIG. 4 with additional possibility for the decoupling of the driveassembly from the torsionally rigid connection between the rotor and thesecondary blade wheel;

FIG. 6 illustrates a further development of an embodiment according toFIG. 4 with additional possibility for the decoupling of the rotor fromthe secondary blade wheel;

FIG. 7 illustrates in schematically greatly simplified depiction a firstembodiment of a combination consisting of a coupling of the rotor withthe primary blade wheel and the secondary blade wheel;

FIG. 8 illustrates in a schematically greatly simplified depiction asecond embodiment of a combination consisting of coupling of the rotorwith the primary blade wheel and the secondary blade wheel.

FIG. 1 illustrates in a schematically greatly simplified depiction afirst possible embodiment of a drive system 1, designed in accordancewith the invention, on the basis of an excerpt from it. The drive system1 comprises a drive assembly 2, which is designed for use in vehiclespreferably as an internal combustion engine 3. Coupled with this is atleast one power transmission unit 4, this comprising, in accordance withthe invention, a starting unit 24, which in turn comprises a startingelement 10 in the form of a hydrodynamic clutch 5. This further has abridging clutch 25 in the form of an engaging and disengaging clutch 26,which is situated parallel to the starting element 10. Further, anelectrical machine 7 is coupled with the drive assembly 2, particularlyits drive shaft 6. This electrical machine involves a so-called startergenerator, which is understood to mean an electrical machine whosearmature or rotor 8 is coupled in a torsionally rigid manner with thedrive shaft 6 at least as little indirectly as possible, that is,directly, or else through further transmission elements and that can beoperated both as generator and as motor. This electrical machine 7accordingly replaces, as its basic function, a starter and a generatorin the drive system.

The drive system 1 further comprises, according to FIG. 1, at least onetransmission 9, which is situated after the hydrodynamic clutch 5. Forthe embodiment depicted in FIG. 1, the hydrodynamic clutch 5 functionsas starting element 10, which, as indicated by the broken line in FIG.1, can be amalgamated with the transmission 9 into a modular unit 27 orelse is integrated in the transmission 9. The starting unit 24 and thetransmission 9 form, in the case depicted, the modular unit 27. Forillustration of the individual coupling possibilities for the electricalmachine 7, the hydrodynamic clutch 5, as starting element 10, and thetransmission 9 are depicted separately. The modular unit 27 comprisingthe two is depicted with a broken line. The hydrodynamic clutch 5comprises a primary wheel 11 and a secondary wheel 12. The hydrodynamicclutch 5 is free of a guide wheel. The primary blade wheel 11 and thesecondary blade wheel 12 form a torus-shaped operating chamber 13 witheach other. For power transmission, the hydrodynamic clutch is at leastpartially filled and preferably completely filled. For control of thepower transmission and particularly of the power input, the fillingratio can be varied. In accordance therewith, a device 14, indicatedhere only by an arrow, is adjoined to the hydrodynamic clutch 5 forcontrol of the filling ratio. In this regard, there exist, according tothe prior art, a plurality of possibilities, which, however, will not bedealt with in detail separately here.

In accordance with the invention, the rotor or armature 8 of theelectrical machine 7, in a first solution variant, is coupled in atorsionally rigid manner with the primary blade wheel 111 of thehydrodynamic clutch 5. This connection is designated by reference 16.Further, the primary blade wheel 11 is connected at least indirectly ina torsionally rigid manner with the drive shaft 6 of the drive assembly2; according to FIG. 1, it is connected directly with the latter. Theconnection between the rotor 8 and the primary blade wheel 11 isdesignated by reference 16. This is constantly present. Accordingly, inthe case depicted, the starter generator or the electrical machine 7 isalways coupled with the drive assembly 2 and the power transmission unit4. Provided for decoupling of the electrical machine 7 from thetransmission 9 is a device 15 for interrupting the power flow betweenthe electrical machine 7 and the transmission 9 for power transmissionwith circumvention of the hydrodynamic clutch. This device involves, asa rule, an engaging and disengaging clutch. This function is assumedhere by the bridging clutch 25. For starting the driving engine 2 here,the bridging clutch 25 is preferably opened. The hydrodynamic clutch 5can already be partially filled. On account of the good cold startbehavior of the hydrodynamic clutch, it does not have a negative effecton the starting operation. Further, there exists the possibility,besides making use of the electrical machine 7 for active reduction ofrotational irregularities, of also providing, in addition, a device forthe damping of vibrations 17, preferably a torsional vibration damper.This is not depicted in detail, but the possible arrangements thereof,references 18.1 to 18.4, are shown by a cross in FIG. 1. The torsionalvibration damper 18.1 can here be arranged, in accordance with anespecially advantageous embodiment, between the drive assembly 2 and theconnection 16 of the electrical machine 7 with the primary blade wheel11 of the hydrodynamic clutch 5. In this case, the irregularities of thedrive assembly 2 are not transmitted into the drive train. A furtherpossibility consists of the arrangement between the electrical machine 7and the transmission 9, it being possible here for the arrangement to bemade in front of as well as behind the bridging clutch 25. These twopositions are designated by references 18.2 and 18.3. The fourthpossibility, designated by reference 18.4, exists in the arrangement ofthe torsional vibration damper in front of the transmission 9; that is,it is situated after both the starting unit 24 and the electricalmachine 7.

For the configuration depicted in FIG. 1, the electrical machine 7 isalways coupled in a torsionally rigid manner with the internalcombustion engine 3. This means that, in this case, when the internalcombustion engine 3 is set into operation, the electrical machine 7always takes up a power fraction, corresponding to its actuation, and isoperated as a generator. This allows constantly the provision ofelectrical energy for the on-board electrical system of the vehicle, forexample, via the internal combustion engine 3. In the decelerating mode,that is, when power flow is regarded as occurring from the drive wheelsto the internal combustion engine, there exists the possibility, bymeans of the bridging clutch 25, when the clutch 5 is emptied, ofdecoupling the transmission 9 from the starter generator, that is, fromthe electrical machine 7. In this case, however, no electrical power canbe obtained from the decelerating power. When the hydrodynamic clutch isfilled, the power flow occurs primarily via the starting unit 24,particularly the hydrodynamic clutch 5, to the internal combustionengine 3; however, here, too, only the rotor 8 is coupled in motion andthe decelerating power is distributed both to the drive assembly 2 andto the electrical machine 7.

For the configuration depicted in FIG. 1, the electrical machine 7 isarranged coaxially to the starting element 10, that is, to thehydrodynamic clutch 5, and thus also to the drive assembly 2. This alsoholds true for the embodiment according to FIG. 2, which is providedwith another additional device for interrupting the power flow betweenthe connection 16 of the starter generator 7 and primary blade wheel 111of the hydrodynamic clutch 5 and the drive assembly 2. This device isdesignated by reference 19. It, too, comprises preferably an engagingand disengaging clutch. The basic construction of the drive system 1otherwise corresponds to that described in FIG. 1, for which reason thesame reference numbers are used for the same elements. The additionalpossibility of interrupting the power flow between the drive assembly 2and connection 16 of the electrical machine 7 and the primary bladewheel 11 of the hydrodynamic clutch 5 creates the possibility of acomplete decoupling of the drive assembly 2 from the remaining drivetrain. Accordingly, this affords still another arrangement possibilityfor a torsional vibration damper, which is designated here by reference18.5. The torsional vibration damper here is arranged between the clutch19 and the drive assembly 2. The electrical machine 7 is accordinglyarranged between two clutches, the clutch 19 and the bridging clutch 25.The possibility is thus afforded of connecting the electrical machineeither with the drive assembly 2 and/or with the transmission 9. Thismakes it possible, when the motor is warm, to start directly, that is,with a closed coupling 19, when the drive assembly 2 is designed as aninternal combustion engine 3. At low temperatures, when the deceleratingmoment of the drive assembly 2, particularly of the internal combustionengine, is very large, preferably both clutches, the clutch 19 and thebridging clutch 25, are first opened. When this is done, initially thearmature or rotor 8 of the electrical machine is highly accelerated andonly then is the first clutch 19 closed. The drive shaft 6 is thenaccelerated and the drive assembly 2, that is, the internal combustionengine, starts all of a sudden. A further decisive advantage of thissolution, particularly the possibility of decoupling the electricalmachine 7 from the internal combustion engine 3, consists of an improvedrecuperation of the braking energy, because the fraction that iseliminated when the drive train and the electrical machine 7 are coupleddirectly with the internal combustion engine 3 owing to internalfriction in the latter, due to the possibility of decoupling of thedrive assembly 2 from the electrical machine 7, can be supplied to thelatter as well. In the coasting mode in higher gears, therefore, thedevice 15 is preferably always actuated in such a way that a couplingbetween the electrical machine 7 and the speed/torque converter unit 9exists. The hydrodynamic clutch 5 is preferably emptied.

The starting unit 24 and the transmission are amalgamated here to formthe modular unit 27. The latter can also further include the clutch 19.Also conceivable, however, is situating the clutch 19 upstream as aseparate device of the modular unit 27.

In regard to the kind of combination of the starting unit 24 and thetransmission 9, there exist no restrictions, that is, in regard to theintegration of the starting unit 24 into the transmission 9,particularly into a part of the housing compartment of the transmission9 or through flange mounting on the housing. In both cases, a completemodular unit 27 is formed.

In the two embodiments according to FIGS. 1 and 2, the electricalmachine 7 can also additionally be used as a booster to assist the driveassembly 2 in providing power by feeding power into the drive system 1.

FIG. 3 illustrates a further modification of a drive system 1, designedin accordance with the invention, according to FIG. 1. Here, the rotor8.3 of the electrical machine 7.3 is not continuously, that is, notconstantly, coupled in a torsionally rigid manner with the primary bladewheel 11.3. The connection 16.3 can accordingly be broken as chosen.Provided for this purpose is a device 20 for the alternative coupling ordecoupling of the rotor of the primary blade wheel 11.3. Said device isdesigned preferably also in the form of an engaging and disengagingclutch. The function and the remaining construction of the drive system1.3 is configured in analogy to that described in FIG. 1, although, inaddition, the power flow between the drive assembly 2.3 and theelectrical machine 7.3 can be interrupted independently of the powertransmission between the drive assembly 2.3 and the starting element10.3 or between the bridging clutch 25 and the transmission; that is,only at times is electrical power made available via the electricalmachine 7.3, depending on the actuation of the device 20. Thearrangement possibilities for integration of a torsional vibrationdamper correspond to those described in FIG. 1 and are designated byreferences 18.1, 18.2, 18.3, and 18.4.

FIG. 4 illustrates another alternative embodiment. The drive system 1.4comprises likewise a drive assembly 2.4 in the form of an internalcombustion engine 3.4, which is coupled with a power transmission unit4.4, comprising a starting unit 24.4, with a starting element in theform of a hydrodynamic clutch 5.4. The hydrodynamic clutch 5.4 is herean integral component of a modular unit 27.4, comprising a transmission9.4, but can be situated upstream of the transmission 9.4 when itfunctions as starting unit 10.4 and is designed as a separate unit andonly be flange-mounted on the housing of the transmission 9.4. In FIG.4, for illustration of the attachment possibilities, the hydrodynamicclutch 5.4 and the transmission 9.4 are depicted as separated in space.Here, too, the electrical machine 7.4 is arranged coaxially with respectto the hydrodynamic clutch 5.4 and accordingly, when it is coupled withthe internal combustion engine 3.4, coaxially with respect to thelatter. The primary wheel 11.4 of the hydrodynamic clutch 5.4 is coupledin a torsionally rigid manner with the drive shaft 6.4 of the driveassembly 2.4. The secondary wheel 12.4 is connected in a torsionallyrigid manner with the speed/torque converter unit. When the hydrodynamicclutch 5.4 is integrated into the modular unit 27.4, the primary bladewheel 11.4 or the element coupled in a torsionally rigid manner with thelatter here forms the transmission input shaft E of the modular unit27.4. The electrical machine 7.4, particularly the armature or rotor8.4, is coupled here in a torsionally rigid manner with the secondarywheel 12.4 and thus also with the transmission 9.4. The starting unit24.4 comprises here, too, a bridging clutch 25.4, which is engagedparallel to the hydrodynamic clutch 5.4. The electrical machine 7.4 isconnected here between the starting unit 24.4 and the transmission 9.4.The rotor 8.4 of the electrical machine 7.4 is always coupled here in atorsionally rigid manner with the secondary blade wheel 12.4 and theoutput 29 of the bridging clutch 25.4. A coupling of the rotor 8.4 withthe drive assembly 2.4 is therefore possible only when the hydrodynamicclutch 5.4 is filled, such as, for example, during the startingoperation, or else when the bridging clutch 25 is closed. For thepurpose of optimal energy recuperation in the coasting mode, thehydrodynamic clutch 5.4 is preferably completely, but at leastpartially, emptied and the bridging clutch 25.4 is opened. In this way,it is possible to produce a complete decoupling of the internalcombustion engine 3.4 from the remaining power transmitting units,particularly the transmission 9.4 and the complete modular unit 27.4.The total power delivered via the transmission 9.4 in the direction ofthe drive assembly 2.4 can thus be supplied to the electrical machine7.4 and converted into electrical power.

When the hydrodynamic clutch 5.4 is emptied, power transmission stilloccurs only from the drive assembly 2.4 to the transmission 9.4 withcircumvention of the hydrodynamic clutch 5.4 and, on account of thetorsionally rigid coupling 28 of the armature or rotor 8.4 of theelectrical machine 7.4 with the secondary blade wheel 12.4, it ispossible to tap a power fraction of the total power made available bymeans of the drive assembly 2.4 for the generation of electrical powerfor the on-board electrical system. If, in the embodiment according toFIG. 4, an emptying of the hydrodynamic clutch 5.4 is still required forthe purpose of energy recuperation, during which, however, ventinglosses due to the coupled motion of the secondary blade wheel 12.4 areregistered, it is possible, through provision of another device 23 forthe alternative interruption of the power flow between the driveassembly 2.5 and the hydrodynamic clutch 5.5, to achieve a completedecoupling of the drive assembly 2.5. In this case, even when thehydrodynamic clutch 5.5 is filled, as depicted in FIG. 5, it ispossible, through the bridging, that is, the synchronization between theprimary blade wheel 11.5 and the secondary blade wheel 12.5, to feed allof the power delivered to the drive train from the wheels to theelectrical machine 7.5 for the generation of electrical power.

Also for the two solutions depicted in FIGS. 4 and 5, there resultdifferent arrangement possibilities of a torsional vibration damper.These are depicted here by references 32.1 to 32.4 for FIGS. 4 and 32.1to 32.5 for FIG. 5. The position 32.1 of the torsional vibration damperis provided by the arrangement between the drive shaft 6.4 or 6.5 andthe hydrodynamic clutch 5.4 or 5.5, respectively, in front of thebridging clutch. Here, the arrangement can be made directly behind or atthe drive shaft 6.4 or 6.1, respectively, but also in front of thebridging clutch 25.4 or 25.5, respectively. The arrangement 32.2 is madedirectly in front of the bridging clutch. Further, according toreference 32.3, the torsional vibration damper can be arranged behindthe bridging clutch 25.4 or 25.5 in front of the electrical machine 7.4or 7.5, respectively, and, according to reference 32.4, behind thebridging clutch 25.4 or 25.5 and after the electrical machine 7.4 or7.5, respectively. The position 24.5 in FIG. 4 illustrates an additionalarrangement behind the device 23 in the form of an engaging anddisengaging clutch and in front of the bridging clutch 25.5

For the solution depicted in FIG. 5, the device 23, as a disengagingclutch, can be a part of the starting unit 24.5 and possibly of themodular unit 27.5 formed from the starting unit 24.5 and thetransmission 9.5. Also conceivable, however, is the constructionalseparation of the device 23 and the modular unit 27.5. In this case, thedevice is arranged in front of the modular unit 27.5. This holds true byanalogy also for the torsional vibration damper 32.1 in FIGS. 4 and 5and 32.2 in FIG. 5.

FIG. 6 illustrates a modification of an embodiment according to FIG. 4.The basic structure corresponds to that in FIG. 4, for which reason thesame reference numbers are used for the same elements. Provided here, inaddition, is a device 22 for the alternative coupling or decoupling ofthe rotor 8.6 of the electrical machine 7.6 from the secondary bladewheel 12.6. Said device is designed preferably in the form of anengaging and disengaging clutch and is arranged in the connection 28between the electrical machine 7.6 and the secondary blade wheel 12.6.The mode of operation corresponds essentially to that described in FIG.4 and is at times disabled by the complete decoupling of the electricalmachine 7.6 from the drive train and thus the drive assembly 2.6 as wellas the hydrodynamic clutch 5.6. The arrangement possibilities for thetorsional vibration dampers, 32.1 to 32.4, correspond to those in FIG.4.

Also when the rotors 8.4, 8.5, and 8.6 are coupled with the secondaryblade wheel 12.4, 12.5, or 12.6, respectively, there exists thepossibility of making use of the electrical machine 7.4, 7.5, or 7.6,respectively, as a booster, that is, for making available additionalenergy to the drive train, and, in this case, for an embodimentaccording to FIG. 6, the clutch 22 has to be closed. Further, theelectrical machine 7.4, 7.5, or 7.6 can be employed for starting thedrive assembly 2.4, 2.5, or 2.6, respectively. In the coasting mode,when there exists a coupling of the rotor 8.4, 8.5, or 8.6 with thesecondary blade wheel 12.4, 12.5, or 12.6, respectively, or thetransmission 9.4, 9.5, or 9.6, respectively, power supplies into theon-board electrical system or into an energy storage device arepossible.

For reasons of clarity in FIGS. 5 and 6, a separate depiction of themodular unit 27 corresponding to FIG. 4 was dispensed with.

FIGS. 7 and 8 illustrate another, third possibility for the attachmentof the electrical machine 7 to the starting unit 24. The basic structureof the drive system, with the drive assembly 2, the starting unit 24,and the subsequently arranged transmission 9 and with the provision of abridging clutch 25, which is engaged parallel to the hydrodynamic clutch5, corresponds to that described in FIGS. 1 to 6. In these embodimentsaccording to FIG. 7 and FIG. 8, however, the electrical machine 7 isarranged in the parallel power branch 30, in which the bridging clutch25 is arranged. The rotor 8.7 of the electrical machine 7.7, accordingto FIG. 7, is connected in a torsionally rigid manner directly, that is,continuously, with the primary blade wheel 11.7, the connection beingdesignated by reference 16.7. Further, the rotor 8.7 is coupled in atorsionally rigid manner with the input 31 of the bridging clutch 25.7.The output 29.7 of the bridging clutch 25.7 is connected with thesecondary blade wheel 12.7 of the hydrodynamic clutch 5.7. Forseparation of the electrical machine 7.7 from the drive assembly 2.7, adevice 19.7 for alternative coupling or decoupling of the connection16.7 with the drive assembly 2.7, which is designed, for example, in theform of an engaging and disengaging clutch, is provided. This solutionmakes possible, when the coupling 19.7 is opened in the coasting mode,independent of the power transmission via the hydrodynamic clutch 5.7 orvia the bridging clutch 25.7, a complete decoupling of the driveassembly 2.7 from the drive train, so that the power supplied to theelectrical machine 7.7 in the coasting mode is not minimized by thedecelerating losses of the driving engine 2.7. For the embodimentaccording to FIG. 8, a device 20.8 for the alternative coupling ordecoupling of the rotor 8.8 from the primary blade wheel 11.8 isintegrated in the connection 16.8, so that, although, here, too, acomplete decoupling of the drive assembly 2.8 during the coasting modeoccurs when power is transmitted only via the power branch described bythe bridging clutch 25.8, the internal combustion engine 3.8 isnonetheless coupled in motion in the coasting mode, when thehydrodynamic clutch is filled, via the latter.

The solutions according to FIGS. 7 and 8 are characterized by theconnection of the rotor 8.7 or 8.8, respectively, both with the primaryblade wheels 11.7, 11.8 and with the input 31 of the bridging clutch, atorsionally rigid coupling 16.7 of the rotor 8.7 with the primary bladewheel 11.7 always existing according to FIG. 7, whereas, according toFIG. 8, it can be broken selectively, that is, at times. For bothsolutions, when the electrical machine 7.7 or 7.8 is used as thestarter, the devices 20.8 or 19.7 are closed, the hydrodynamic clutch ispreferably completely, at least, however, partially, emptied, and thebridging clutches 25.7, 25.8 are opened. As a booster, the clutches 5.7,5.8 are then filled or the bridging clutches 25.7, 25.8 are closed. Forenergy recuperation in the braking mode or in the coasting mode, theconnection between the rotor 8.7 or 8.8 and the drive assembly is cutoff; that is, the devices 19.7 and 20.8 are opened. Resulting for thearrangement of vibration dampers are the following possibilities, whichare designated for FIG. 7 by the references 33.1 to 33.6 and for FIG. 8by 33.1 to 33.5. Here, the arrangement of the torsional vibrationdampers 33.3 in each case is made between the rotors 8.7 and 8.8 and theinput 31 of the bridging clutches 25.7 and 25.8, respectively. Thearrangement of the torsional vibration damper 33.4 is made between thebridging clutches 25.7, 25.8 and the coupling with the secondary bladewheels 12.7, 12.8; the arrangement of the torsional vibration damper33.5 is made between the connection of the output 29.7 or 29.8 of thebridging clutch 25.7 or 25.8, respectively, and the secondary bladewheel 12.7 or 12.8, respectively, with the transmission 9.7 or 9.8,respectively.

The torsional vibration dampers 33.1 are situated downstream from thedrive assembly 2.7 or 2.8 and are arranged in the connection of thelatter with the connection 16.7 or 16.8, respectively, between the rotor8.7 or 8.8, respectively, and the primary blade wheel 11.7 or 11.8,respectively. Reference 33.2 denotes the arrangement in front of therotor 8.7 or 8.8 in the connection 16.7 or 16.8, respectively. Reference33.3 in FIG. 7 corresponds to an arrangement in front of the connection16.7, but after the device 19.7, whereas reference 33.3 in FIG. 8corresponds to an arrangement in the connection 16.8 in front of thedevice 20.8.

List of Reference Numbers

-   1; 1.3; 1.4; 1.5; 1.6; 1.7; 1.8 Drive system-   2; 2.3; 2.4; 2.5; 2.6; 2.7; 2.8 Drive assembly-   3; 3.3; 3.4; 3.5; 3.6; 3.7; 3.8 Internal combustion engine-   4; 4.3; 4.4; 4.5; 4.6; 4.7; 4.8 Power transmission unit-   5; 5.3; 5.4; 5.5; 5.6; 5.7; 5.8 Hydrodynamic clutch-   6; 6.3; 6.4; 6.5; 6.6; 6.7; 6.8 Drive shaft-   7; 7.3; 7.4; 7.5; 7.6; 7.7; 7.8 Electrical machine-   8; 8.3; 8.4; 8.5; 8.6; 8.7; 8.8 Armature, rotor of the electrical    machine-   9; 9.3; 9.4; 9.5; 9.6; 9.7; 9.8 Speed/torque converter unit-   10; 10.3; 10.4; 10.5; 10.6; 10.7; 10.8 Starting element-   11; 11.3; 11.4; 11.5; 11.6; 11.7; 11.8 Primary blade wheel-   12; 12.3 Secondary blade wheel-   13; 13.3 Torus-shaped operating chamber-   14 Device for controlling the filling ratio-   15 Device for alternative interruption or realization of the power    flow between the electrical machine and the transmission modular    unit-   16 Connection between the rotor of the electrical machine and the    primary blade wheel of the hydrodynamic clutch-   17 Device for damping of vibrations-   18.1; 18.2; 18.3; 18.4; 18.5 Torsional vibration damper-   19; 19.7 Device for the alternative coupling or decoupling of the    connection 16 from the drive assembly-   20; 20.8 Device for the alternative coupling or decoupling of the    rotor from the primary blade wheel-   21 Device for the alternative coupling or decoupling-   22 Device for the alternative coupling or decoupling of the rotor of    the electrical machine from the secondary blade wheel-   23 Device for the alternative interruption or realization of the    power flow between the drive assembly and the hydrodynamic clutch as    well as the electrical machine-   24 Starting unit-   25 Bridging clutch-   26 Engaging and disengaging clutch-   27; 27.4 Transmission modular unit-   28 Connection between the electrical machine and the secondary blade    wheel-   29.7; 29.8 Output of the bridging clutch-   30 Power branch-   31 Input of the bridging clutch-   32.1; 32.2; 32.3; 32.4; 32.5 Torsional vibration damper-   33.1; 33.2; 33.3; 33.4; 33.5; 33.6 Torsional vibration damper

1-31. (canceled)
 32. A drive system for a motor vehicle comprising: adrive assembly; at least one power transmission unit having at least onestarting element and being coupled with said drive assembly; and anelectrical machine having a rotor and being coupled at least indirectlywith said drive assembly, wherein said at least one starting element hasa hydrodynamic clutch and a bridging clutch, wherein said rotor iscoaxial to said hydrodynamic clutch, and wherein said rotor iscoupleable with said hydrodynamic clutch in a torsionally rigid manner.33. The drive system of claim 32, wherein said hydrodynamic clutch canbe operated when only partially filled with a medium.
 34. The drivesystem of claim 32, further comprising a fill ratio controller thatcontrols a filling ratio of said hydrodynamic clutch.
 35. The drivesystem of claim 32, wherein said hydrodynamic clutch comprises a primaryshell, a primary blade wheel, a secondary blade wheel and is free of aguide wheel, wherein said rotor is coupled in a torsionally rigid mannerwith said primary blade wheel or said rotor is coupleable with saidprimary shell in a torsionally rigid manner, said primary shellsurrounding said secondary blade wheel in an axial direction andpartially in a radial direction.
 36. The drive system of claim 35,wherein said rotor is operably connected with said primary blade wheelor said primary shell.
 37. The drive system of claim 36, wherein saidrotor forms an integral modular unit with said primary blade wheel orsaid primary shell.
 38. The drive system of claim 35, further comprisinga transmission and a first coupling device, wherein said first couplingdevice is downstream of said hydrodynamic clutch and can selectivelycouple or decouple said rotor with said transmission.
 39. The drivesystem of claim 38, wherein said first coupling device is a clutch. 40.The drive system of claim 38, wherein said drive assembly has a driveshaft, and wherein said rotor is connected in a torsionally rigid mannerwith said drive shaft.
 41. The drive system of claim 38, furthercomprising a second coupling device for coupling or decoupling of saidrotor from said drive assembly.
 42. The drive system of claim 41,wherein said second coupling device is between said rotor and saidprimary blade wheel or said primary shell.
 43. The drive system of claim41, further comprising a connection between said rotor and saidhydrodynamic clutch, wherein said second coupling device is between saiddrive assembly and said connection.
 44. The drive system of claim 41,wherein said second coupling device is a clutch.
 45. The drive system ofclaim 32, wherein said hydrodynamic clutch comprises a primary bladewheel and a secondary blade wheel and is free of a guide wheel, andwherein said rotor can be connected in a torsionally rigid manner withsaid secondary blade wheel.
 46. The drive system of claim 45, whereinsaid secondary blade wheel and said rotor are operably connected. 47.The drive system of claim 46, wherein said secondary blade wheel andsaid rotor are an integral modular unit.
 48. The drive system of claim45, further comprising an internal combustion engine and an interruptingdevice for interrupting a power flow between said internal combustionengine and said rotor, said interrupting device being actuated at leastwhen said power flow is transmitted via said bridging clutch.
 49. Thedrive system of claim 45, further comprising an internal combustionengine and an interrupting device for interrupting a power flow betweensaid internal combustion engine and said rotor, said interrupting devicebeing actuated at least when said power flow is transmitted via saidhydrodynamic clutch.
 50. The drive system of claim 48, wherein saidinterrupting device is defined in part by said bridging clutch.
 51. Thedrive system of claim 48, further comprising a connection between saidprimary blade wheel and said rotor, wherein said interrupting device hasa disengaging device between said drive assembly and said connection.52. The drive system of claim 48, wherein said interrupting device has athird coupling device for selectively coupling or decoupling of saidrotor from said secondary blade wheel.
 53. The drive system of claim 48,wherein said interrupting device has a third coupling device forselectively coupling or decoupling of said rotor from said primary bladewheel.
 54. The drive system of claim 45, further comprising a vibrationdamper.
 55. The drive system of claim 54, further comprising aconnection between said primary blade wheel and said rotor, wherein saidvibration damper is between said drive assembly and said connection. 56.The drive system of claim 54, wherein said vibration damper is betweensaid rotor and said primary blade wheel.
 57. The drive system of claim54, wherein said vibration damper is between said rotor and saidsecondary blade wheel.
 58. The drive system of claim 54, wherein saidvibration damper is in front of said bridging clutch or after saidbridging clutch.
 59. The drive system of claim 54, further comprising aconnection between said secondary blade wheel and said rotor, whereinsaid vibration damper is behind said connection.
 60. The drive system ofclaim 54, further comprising a connection between said secondary bladewheel and said bridging clutch, wherein said vibration damper is behindsaid connection.
 61. The drive system of claim 54, wherein saidvibration damper is a hydraulic torsional vibration damper.
 62. Thedrive system of claim 32, further comprising a transmission and astarting unit, said transmission being operably connected to said driveassembly, said starting unit being downstream of said transmission,wherein said hydrodynamic clutch is a component of said starting unit.63. The drive system of claim 62, wherein said starting unit has acasing, wherein said transmission has a housing, and wherein said casingis flange-mounted on said housing to form a modular unit.
 64. The drivesystem of claim 63, wherein said housing of said transmission has atransmission compartment in which said starting unit is integrated intosaid transmission.
 65. The drive system of claim 32, further comprisinga transmission operably connected to said drive assembly, wherein saidtransmission is an automated shift transmission.
 66. The drive system ofclaim 32, further comprising a transmission operably connected to saiddrive assembly, wherein said transmission is an automatic transmission.67. The drive system of claims 32, further comprising a transmissionoperably connected to said drive assembly, wherein said transmission isa CVT transmission.